Ribbed drafting aprons with recessed supporting rolls



E. ANDREANI June 25, 1968 RIBBED DRAF'TING APRONS WITH RECESSED SUPPORTING ROLLS Filed Oct. 11, 1966 valalw opllp ATTORNEYS N \A- 7- B [-05 NM 72 lNl ENTOE:

Euqemo ANDREANS MMMgKMM United States Patent "ice 3,389,437 RIBBED DRAFTING APRONS WITH RECESSED SUPPORTING ROLLS Eugenio Andreani, Bergamo, Italy Continuation-impart of application Ser. No. 518,863,

Jan. 5, 1966. This application Oct. 11, 1966, Ser.

4 Claims. (Cl. 19-252) ABSTRACT OF THE DISCLDSURE A pair of engagingly cooperating endless pliable drafting aprons each having a pair of ribs projecting inwardly from the inner surface of the apron and spaced inwardly from the sides of the apron and received by annular grooves in supporting rollers to increase traction between the aprons and the supporting rollers and to eliminate slippage therebetween during rotation, and wherein the corresponding ribs on the pair of aprons are arranged in cooperating pairs so that each rib of one of the aprons is in opposing relation to a corresponding rib of the other apron and lies in a common plane therewith.

This application is a continuation-in-part of my copending application Ser. No. 518,863, filed Jan. 5, 1966, and entitled, Textile Apron Stabilizing and Cleaning System for Drafting Units, now Patent No. 3,346,926.

This invention relates to apparatus for drafting textile fibers and, more especially, to an improved mounting and guiding means for endless belt drafting aprons to insure proper tracking of and traction between cooperating aprons with respect to each other.

As is well known, textile slivers are drawn into the drafting unit of a drawing frame from cans which have been doffed from different carding machines, with the result that the counts or sizes of all the slivers are not perfectly identical. In other words, the slivers being drawn from different cans are different from each other. Consequently, as the textile slivers pass between upper and lower endless drafting aprons, they are of various thicknesses, and even though the lower apron is supported on rigidly mounted rolls and the upper apron is yieldably urged toward the lower apron throughout its width, it has been found that, heretofore, the differences in the thickness of slivers passing between the upper and lower aprons has caused a relative lateral shifting movement between the upper and lower aprons nad has caused longitudinal slippage between the aprons and their supporting rollers. This difficulty is brought about by the fact that the usual springs or other means which apply yieldable downward pressure to the upper apron toward the lower apron apply such pressure perpendicular to the mean plane of the proximal run of the lower apron, but when the different thicknesses of slivers are passing between the belts, the force being applied to the upper apron is no longer perpendicular to the sliding plane of the fibers passing between the belts, thus tending to force either or both of the upper and lower aprons laterally of their intended, normal, path of travel. This not only sometimes results in an undesirable relative lateral displacement between the upper and lower drafting aprons, but it also applies an undesirable transverse rubbing action to the fibers. Additionally, the greater the speed of the aprons, the greater is the tendency for the prior art types of aprons to slip or shift laterally relative to each other when slivers of different thickness are being drafted therebetween, thus limiting the speed at which the corresponding drafting mechanism could otherwise be operated.

In order to prevent side slipping of each apron relative to their supporting rollers, the drafting aprons disclosed in 3,389,437 Patented June 25, 1968 my said copending application each are provided with spaced apart parallel endless ribs integral therewith and projecting inwardly therefrom, and the aprons are mounted on respective sets of rollers each having annular peripheral grooves therein of substantially the same size and configuration as the ribs and mating therewith.

The construction of drafting aprons and cooperating supporting rollers of said copending application has improved the tracking of the aprons. In order to improve further the operation of the endless belt drafting aprons and to insure that the aprons will not slip in their directions of rotation relative to the apron-supporting rollers, it is an object of this invention to provide drafting aprons of yieldable rubber-like material which have broad flat ribs on the inner surfaces thereof and wherein opposite side edges of each rib are beveled or formed at a slight angle of about ten to about twenty degrees with respect to corresponding radial planes of the aprons. The supporting rollers for the aprons have annular peripheral grooves therein for receiving the ribs of the aprons, and opposed side walls of the annular grooves are also beveled or formed at a slight angle of about ten to about twenty degrees with respect to corresponding radial planes of the rollers. By such arrangement, when the aprons are placed under tension and are traveling in engagement with the rollers, the beveled edges of the ribs on the aprons mold or conform to the beveled side walls of the grooves of each roller, even though, for constructive reasons, the angles of the side walls of each peripheral groove differ slightly from the angles of the side walls of the other peripheral grooves, thus providing greater traction between the aprons and the supporting rollers.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawings, in which:

FIGURE 1 is a longitudinal vertical sectional view through the drafting unit of a drawing frame equipped with the novel apron drafting system of the instant invention;

FIGURE 2 is a fragmentary vertical sectional view taken substantially along line 22 in FIGURE 1;

FIGURE 3 is an enlarged detail sectional view through a portion of one of the aprons and the corresponding rib projecting inwardly therefrom;

FIGURE 4 is a fragmentary view illustrating the configuration of the recess formed in a corresponding supporting roller for receiving the rib shown on the apron in FIGURE 3; and

FIGURE 5 is a schematic elevation of the apron drafting system showing how different thicknesses of slivers between the upper and lower aprons effect variation in the direction in which the force is effective upon the aprons and the slivers.

Referring more specifically to the drawing, the drafting unit and associated apron drafting system of FIGURES 1, 2 and 5 are essentially as disclosed in my said copending application Ser. No. 518,863, with the exception that the apron cleaning system of said copending application is omitted in the instant application. Accordingly, only a general description of the drafting unit shown in the accompanying drawing will be described, and reference is made to said copending application for a more detailed description thereof.

As shown in FIGURE 1, the numerals 10 and 11 indicate top and bottom feed rolls of the drafting unit which feed slivers or other textile fibers S between the proximal runs of upper and lower endless belt drafting aprons 12, 13 from whence the slivers are drafted through a pair of top and bottom delivery drafting rolls 14, 15. As is usual, bottom drafting rolls 11, 15 are driven by conventional means, not shown, but well known in the art, with roll being driven at a faster surface speed than roll 11.

An apron-supportin bottom roller 16 is also driven by such conventional means at a predetermined speed relative to that of drafting rolls 11, 15. Apron-supporting roller 16, along with a tensioning roller 17, a nose bar or roller 23, and an intermediate slip roller 21 between rollers 16, 29, have the endless lower apron 13 mounted thereon. A second tension roller 22 engages the outer surface of apron 13 at a point spaced substantially below the level of drafting rolls 11, 15.

Tension rollers 17, 22 are journaled on common blocks 24, which are interconnected by a rigid bar 26. Blocks 24 are journaled on the frame 27 of the drafting unit and are locked in adjusted position so as to maintain lower drafting apron 13 under proper tension, as by means of a lock nut 3h. The specific construction and manner of operation of tension rollers 17, 22 may be such as is shown in the copending application of Gianfranco Andreani, Ser. No. 385,689, filed July 28, 1964, now Patent No. 3,303,534, and entitled Double Apron Drafting System for Drawing Frames, to which reference is made for amore detailed disclosure of the type drafting system described herein, Rolls 10, 11, 14, 15, 16, 20, 21 are supported in corresponding roll stands, generally designated at 31, carried by the frame 27 of the textile machine.

The upper endless belt drafting apron 12 is carried by a top cradle broadly designated at 35 and comprising a pair of end plates or blocks 36, 36', each of which preferably is shaped substantially according to the contour of the outer surface of upper or top apron 12. End blocks 36, 36 are spaced apart a distance substantially equal to or slightly greater than the width of upper apron 12. Rear and front portions of upper apron 12 are supported by respective rear and front top-apron-supporting rollers 37, 38 disposed above the respective bottomapron-supporting rollers 16, so as to form a bottom run of the top apron 12 which normally extends substantially parallel with and in close proximity to or in engagement with the top run of bottom apron 13.

The rear top-apron-supporting roller 37 may be suitably journaled in end blocks 36, 36 of cradle and corresponding rear portions of end blocks 36, 35' may be suitably guided for vertical movement in corresponding bearing blocks 31 in the manner shown in said lastnamed copending application, for example. Thus, cradle 35 is, in effect, mounted for pivotal movement about the axis of rear apron-supporting roller 37. Opposite ends of front top-apron-supporting roller 38 also may be journaled in end blocks 36, 36.

The upper portion of top apron 12 (FIGURES 1 and 2) extends over a tensioning roller whose opposite ends may be journaled on stub shafts 46, only one of which is shown in FIGURE 1. The reduced outer end portions of stub shafts 46 may be secured in vertically adjusted position by screws 50 which loosely penetrate the upper portions of blocks 36, 36 and may be threaded through reduced portions of the corresponding stub shafts 46 for raising and lowering the reduced ends of the stub shafts 46 in corresponding slots 51 formed in end blocks 36, 36, and thereby raising or lowering the top tensioning roller 45 to control the tension in endless top apron 12. A top slip roll 52 may be provided for cooperating with bottom slip roll 21 and the proximal runs of aprons 12, 13 passing therebetween. Reduced opposite ends of top slip roll 52. may loosely penetrate slots 53 provided in end blocks 36, 36' and may be journaled and mounted for vertical movement in corresponding bearings 31 in the manner disclosed in said copending applications.

Spaced forwardly of and extending substantially parallel with rear top-apron-supporting roller 37 is a rod or bar 60, the opposite ends of whose enlarged body are engaged by end blocks 3 36 of cradle 35 to aid in maintaining the end blocks .36, 36' in predetermined spaced relationship. Bar 69 is preferably positioned so that it is not engaged by endless upper apron 12. Opposed ends of bar 6% are provided with reduced portions 61 thereon which penetrate blocks 36, 36' and are preferably threaded for the reception of nuts 62 thereon to secure the end blocks 36, 36 against the opposed ends of the enlarged portion of bar 61' In order to apply downward pressure to the cradle and bars 36, 36' and to thereby apply yielding downward pressure to the upper apron 12 toward the lower apron 13 in a direction normally perpendicular to the mean substantially horizontal plane of the upper run of endless lower drafting apron 13, each outwardly projecting reduced portion 61 of bar (it) is engaged by a weight or pressure means shown in the form of a spring loaded plunger 63. Each plunger is urged downwardly against the corresponding reduced portion 61 of bar 63 by a suitable spring 64 whose tension may be adjusted by means of a lock nut 65. Each spring 64 may be carried by a fixed arm or bar 67 which may be constructed and supported in fixed relation to frame 27 in the manner fully disclosed in Gianfranco Andreanis said copending application Scr. No. 385,689, now Patent No. 3,303,534.

As heretofore stated, slivers being directed to the drafting unit are drawn from cans into which the slivers have been directed from different carding machines so that the counts or sizes of the different slivers consequently are different from one another. By way of example, it will be observed in FIGURE 5 that the slivers S shown in cross-section therein are of different thicknesses with the slivers adjacent the right-hand portions of aprons 12, 13 being substantially thicker than the slivers adjacent the left-hand portions thereof. As a consequence of the thicker slivers being adjacent the righthand portions of the aprons 12, 13, and since the pressure exerted by the plungers 63 is substantially equal at each of the end blocks 36, 36, the right-hand portion of upper apron 12 in FIGURE 5 is spaced upwardly from the lower belt 13 to a greater extent than the left-hand portion thereof. Thus, the spring loaded plungers 63 transmit to the lower belt a force which is no lower perpendicular to the sliding plane of the fibers or slivers S, but which is inclined by a certain angle. This transmitted force thus is converted from a force perpendicular to the sliding plane or path of the slivers to a force F parallel to said plane which, by reaction, generates an opposite force F on the upper apron 12. In the absence of any means to prevent relative transverse or lateral movement of the aprons 12, 13, it can be appreciated that the forces F, F, being effective in opposite directions laterally of the path of travel of the fibers or slivers S, would cause the aprons 12, 13 to move in opposite directions laterally of the path of travel of the slivers S therebetween.

Therefore, and as disclosed in my said copending application Ser. No. 518,863, in order to prevent aprons 12, 13 from sliding sideways or transversely relative to each other and relative to the rollers on which they are mounted, the aprons, which are made from a pliable or stretchable plastic material such as rubber or the like, have respective pairs of inwardly projecting broad fiat strips, ribs or ridges 7t 71 formed integrally with and projecting inwardly from the inner surfaces thereof and which engage corresponding annular peripheral recesses or grooves 72, 73 formed in the peripheries of the respective sets of rollers 37, 38, 45, 52 and 16, 17, 20, 21 about which the respective aprons 12, 13 are mounted under tension. The thickness of each rib 7t 71 is about equal to or slightly less than the depth of the respective annular grooves 72, 73 so the thin bodies of the aprons 12, 13 are in contact with the straight non-recessed portions of the corresponding apron-supporting rollers.

It will be noted in FIGURE 4 that the annular groove 72, which is representative of all the annular grooves 72, 73 of the apron-supporting rollers, is of a shape similar to the cross-sectional configuration of corresponding projecting strip or rib 70 shown thereabove in FIGURE 3. The latter rib 70 shown in FIGURE 3 is representative of all the ribs 70, 71. The annular grooves 72, 73 con stitute housings for the ribs 70, 71 to maintain the aprons in proper position during their travel while eliminating any sideslip of the aprons. The ribs or strips 70, 71 are spaced inwardly a short distance from the corresponding distal edges of the aprons 12, 13 so that the side walls of the grooves 72, 73 formed in corresponding rollers engage both side walls of the corresponding ribs 7 0, 71.

The apparatus thus far described is substantially as disclosed in my said copending application Ser. No. 518,863. Now, in order to improve the traction between the endless aprons 12, 13, and especially between the driven apron-supporting roller 16 and the lower apron 13, so as to further insure that there is no slippage or relative longitudinal movement between the aprons and the corresponding supporting rollers and so as to ifacilitate high speed operation while minimizing the generation of heat by rotation of the aprons against the supporting rollers, the opposite side edges of each inwardly projecting rib 70, 71 are beveled or formed at an angle with respect to the radial planes of the corresponding aprons so that opposed edges of each rib converge away from the bodies of the respective aprons. Further, the opposed side walls of each annular groove 72, 73 in each corresponding apron-supporting roller are also beveled or formed at a slight angle corresponding as nearly as practicable with the angle of the opposed side edges of the corresponding ribs 70, 71, with opposed side walls of each annular groove extending outwardly from the respective roller in diverging relationship. The outer extremities of the beveled opposed side walls of each annular groove are spaced apart a distance about equal to the width of the corresponding apron rib at its juncture with the body of the corresponding apron. Also, corresponding ribs on the pair of aprons are arranged in cooperating pairs, as shown in FIGURE 2, with each rib of one of the aprons being in opposing relation to a corresponding rib of the other apron and lying in a common plane therewith.

As shown in FIGURE 3, the opposed side walls of the rib 70 each extend at a slight angle A, of about fifteen degrees or within about ten to twenty degrees with respect to the radial plane of the corresponding apron, and the opposed walls of the annular groove 72 in the apron-supporting roller of FIGURE 4 also extend at a similarly slight angle with respect to the radial plane of the corresponding apron-supporting roller; i.e., with respect to imaginary lines perpendicular to the axis of the corresponding roller. The angle A of each side wall of each rib 70, 71 is constant throughout the length of the inner peripheral surface of the corresponding apron. However, for constructive reasons, the angle B varies somewhat from one apron-supporting roller to the other according to its diameter. In other words, it is unlikely that the angle B of each side wall of each apron-supporting roller would be exactly the same even though this is desirable. However, since the aprons 12, 13 are highly tensioned by the adjustment of the respective tensioning rollers 45, 17, the consequent stretching of the endless aprons causes the ribs or strips 70, 71 thereon to set firmly in the corresponding annular grooves of the respective apron-supporting rollers so that the angle A of the opposed side walls of each strip or rib 70, 71 will conform with the angle B of the annular grooves in each roller as successive portions of the aprons engage the respective rollers, thus greatly increasing the friction between the aprons and the respective apron-supporting rollers. The ribs 70, 71 increase the tensile strength of the corresponding aprons 12, 13 so the fiat major portions of the endless aprons between and outwardly of the respective pairs of ribs may be relatively thin and thereby facilitating the use of apron-supporting rollers of relatively small diameters.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

1. In a textile drafting apparatus having a pair of engagingly cooperating endless pliable belt drafting aprons and a plurality of spaced apart supporting rollers about which each of the aprons are looped under tension for movement therearound, the improvement comprising at least two spaced apart parallel endless r-ibs formed integral with and projecting inwardly from each of said aprons along their respective inner peripheral surfaces, said ribs being spaced inwardly from opposite side edges of each of the aprons, each rib of one of said aprons being in opposing relation to a corresponding rib of the other apron and lying in a common plane therewith, said supporting rollers each having annular peripheral grooves therein spaced inwardly from opposite ends of the rollers and being of substantially the same size and configuration as the ribs of the respective aprons and mating therewith to prevent side slipping of the aprons relative to the supporting rollers and to permit the inner peripheral apron portions between the ribs to frictionally contact the rollers for added frictional engagement, the opposite side edges of each rib being beveled and converging inwardly away from the aprons, each roller having spaced side walls defining each peripheral groove and said walls of each groove being beveled and diverging outwardly with respect to the corresponding roller so as to increase the traction between the aprons and the supporting rollers and eliminate slippage therebetween during rotation thereof.

2. Apparatus according to claim 1, wherein the beveled opposite side edges of each rib each extend at an angle of about fifteen degrees with respect to the corresponding radial plane of the apron, and wherein each of the side walls of each peripheral groove also extends at an angle of about fifteen degrees with respect to corresponding radial planes of the corresponding supporting rollers.

3. Apparatus according to claim 1, wherein the beveled opposite side edges of each rib each extend at an angle of about ten to twenty degrees with respect to the corresponding radial plane of the apron, and wherein each of the side walls of each peripheral groove also extends at an angle of about ten to twenty degrees with respect to the corresponding radial planes of the corresponding supporting rollers.

4. Apparatus according to claim 3, wherein the beveled side walls of the peripheral grooves of at least one of said supporting rollers extend at different angles than the beveled walls of the peripheral grooves of at least one other of said supporting rollers, and wherein said drafting aprons are maintained under tension by said plurality of supporting rollers and are made from a rubber-like material so the opposite side edges of the ribs conform to the angular configuration of the side walls of the grooves being engaged thereby during rotation of the drafting apron.

References Cited UNITED STATES PATENTS 207,626 9/ 187 8 Sargent 74-229 2,074,556 3/ 1937 Pilz 19--245 2,145,771 1/1939 McCartney 198-202 FOREIGN PATENTS 945,436 12/ 1963 Great Britain.

ROBERT R. MACKEY, Acting Primary Examiner.

I. C. WADDEY, Assistant Examiner. 

